Clutch device



May 20, 1941.

H. P. HOLT CLUTCH DEVICE Filed July 15, 1940 INVENTOR. ROLD F. Hour M A ATTORNEY.

Patented May 20, 1941 CLUTCH DEVICE Harold P. Holt, New York, N Y., assignor to Fain banks, Morse 82 00., Chicago, 111., a corporation of Illinois Application July 15, 1940, Serial No. 245,515

4 Claims.

This invention relates to improvements in clutch devices and more particularly to that type of clutch embodying means for effecting automatic disengagement of the driving and driven members after the driven member has completed a predetermined number of revolutions.

Devices of this character are frequently employed in connection with the control of automatic or semi-automatic machines, as for example, recording scales wherein an electric motor is employed to drive printing mechanism. In such apparatus a key or the like is manually depressed to initiate operation of the printing mechanism, and after the cycle of operations necessary to effect a printed record of the weight value has been completed clutch means automatically disconnects the printing mechanism from its driving motor. The clutch means of the present invention is an improved form of the device described in U. S. Patent No. 2,070,011, of February 9, 1937, to Harlan A. Hadley and Guldbrand Guldbrandsen, and illustrated in Figs. 3 and 4 thereof.

It has been found that in the former device when the clutch actuating member, the key aforesaid, is quickly depressed and released the clutch parts do not properly engage each other. In other words the key is required to be held in depressed condition for an appreciable period toenable the clutch properly to function, whereas it is desired that the mechanism function when initiated. by a momentary actuation of the starting key. The provision of an improved clutch control mechanism for obtaining the latter result is the principal object of the present invention.

Another object resides in the combination of an improved clutch control of the character described with a switch for controlling energiz'ation of the driving motor. Other objects and advantages will appear as the description proceeds.

In the drawing,

Fig. 1 is a partly sectioned, side elevational view of the means of my invention, the section line appearing as l-I of Fig. 2;

Fig. 2- is a top plan view of, the means of my invention;

Fig. 3 is a side View of the clutch mechanism with the side cover plate of the clutch housing removed, and

Fig. 4 is a side View of the clutch and. switch assembly with the operating parts shown in their respective positions immediately following actuation of the starting key.

Referring now by numerals ofreference'to the dramng, 5 designates the front wall and 6% the base of any suitable frame of housing structure for the means hereinafter described. An electric motor M has a shaft 1 shown connected by a suitable coupling 8 to the hub 9 of a ratchet wheel Hi, which is the driving member of the clutch assembly designated generally H. For simplicity and convenience of. description, motor M is shown as being directly connected to the ratchet wheel ill, but it will be understood that suitable speed -reduction gearing may, and usually will be interposed between the said motor and wheel. Ratchet wheel to is disposed centrally within a drum or circular clutch housing 52 having an axially projecting hub l3 by which the drum is mounted on the end of a shaft M, a setscrew l5 securing the drum for rotation with the shaft I l. The drum i2 is normally closed by an end plate i'l secured thereto, the end plate having a central opening through which the hub or stub shaft 9 of the ratchet wheel Ill outwardly projects for connection with the coupling assembly 8. As described thus far it will be understood that the ratchet Wheel I0 is the driving component of the wheel. When so engaged an operative connection exists between the ratchet wheel and housing so that rotation'of the Wheel (the normal direction of. which is counterclockwise in the present example) is transmitted to the housing and driven shaft M. Opposite its toothed end pawl l9 terminates in a finger 22 which projects substantially radially, outwardly from the clutch housing through an opening 23 formed in the rim of the said housing. Rocking movement of the pawl against the action of spring 2|, or in a direction to release the toothed end 20 from the ratchet wheel is limited by the lateral abutment of pawl finger 22 with the edge 24 of the drum opening 23, a condition illustrated in Fig. 3.

As a means for controlling the clutch there is provided a control lever 25 fulcrumed' on a pin 26 carried by a vertical bracket arm 21, the forward end of the lever projecting through an opening 28 in the front wall 5 of the housing structure and havinga finger piece in the form of a short bar 29 disposed on its forward end. At its opposite extremity lever 25 has a depending nose portion 30, also referred to as a pawl trip, the under surface 3| of which normally rides on the rim of the clutch housing. The depending nose portion presents an obstruction in the path of movement of the outwardly projecting pawl finger 22. Accordingly, in the course of rotation of the clutch housing the pawl finger will be carried into abutment with, and its movement then restrained by the nose 30. The clutch housing, however, will continue to be turned by the ratchet wheel, causing rocking movement of the pawl relative to the clutch housing until such relative movement ef fects a release of. the pawl from the ratchet wheel. Thereafter, the driven members of the clutch will remain stationary until lever 20 is actuated to raise its nose portion 33 out of engagement with pawl finger 22. When thusly freed, pawl I9 moves under the influence of spring 2| into engagement with the ratchet wheel to lock the clutch housing for rotation with the ratchet Wheel. Obviously, if the nose 30 is held in raised position so as to be clear of the pawl finger 22, the clutch components will remain interlocked.

For insuring positive action of the clutch when the control lever is tripped by a momentary force applied to the finger piece, as is the intended method for initiating actuation of the mechanism, the following means are provided. Mounted on the outer face of the clutch housing end plate I7 is an arcuate arm 32 which is mounted to pivot about a screw 33 that extends through one end of the arm 32 and is secured to the clutch housing at a point substantially diametrically opposite the projecting pawl finger. Formed on arm 32 near the end thereof opposite its pivoted extremity, is a cam or detent 34. Such detent projects radially beyond the periphery of the clutch housing and is defirfled by a radial shoulder 35 and a camming edge 38 which slopes from a high point 37 at said shoulder 35 to merge with the outer edge of the arm which may be substantially coincident with the periphery of the clutchhousing. The detent 34 coacts with a pin 38 that projects laterally from the lever nose 30, the pin 38 presenting an abutment for engagement with the shoulder 35 when the control lever is in normal position (Fig. 1). A tension spring 39 connects at one end to a pin 40 on the side of the housing end plate and at the opposite end to the free end of the pivoted arm 32, tends to draw the detent 34 in the normal direction of clutch rotation. Such pivotal movement of the detent relative to the clutch housing is limited by a screw 4| which projects laterally from the housing end plate, through an arcuate slot 42 formed in the arm 32.

Associated with the clutch control lever 25 is a motor control switch, designated generally at 43. Such switch comprises a bar 44 of insulating material secured horizontally to the bracket arm 21 in overlying relation to the control lever. Secured to the upper and lower surfaces of bar 44 are flexible conducting strips 45 and 46 having coacting contact buttons 4'! near the ends thereof. The switch 43 is connected in the motor supply circuit, indicated by conductors 48, and serves to control the energization of said motor. A block 49 of insulation is secured to the control lever and is arranged to engage the under surface of conductor strip 46 and move the same into contact with its companion strip.

A spring 50 acting on the control lever tends to urge the lever to switch-open position.

Describing the operation of the described means, initially, the nose 30 of the control lever is lodged in the housing recess 23 against the pawl finger 22 (Fig. 3), the pawl [9 being thusly held free of the ratchet wheel (see Fig. 3), and detent 34 is held in a cooked position (see Fig. 1) by pin 38. the aforesaid switch, pawl and detent conditions having been attained at the end of a previous operating cycle. Now, when the control lever 25 is actuated by depression of its finger piece 29, first, switch 43 is caused to close and start operation of the motor, then detent 34 is released and springs to a position underlying. the pin 38, acting temporarily to hold the nosed portion of the control lever in an elevated position. Concurrentlywith such detent action the nose 30 releases the pawl finger 22 and the pawl swings, under the influence of its spring, into operative engagement'with the ratchet wheel. Thereupon the clutch housing begins to rotate and pin 38 rides oif of the edge 33 of the detent, yet the nosed end ofthe control lever is held elevated to maintain the motor switch closed, by the bearing engagement of nose 30 on the housing rim. Rotation of the housing continues for one revolution or until the housing opening. 23 again comes into registration with the nose 30.

Having described my invention, what I claim and desire to secure by Letters Patent is:

1. In a clutch assembly including a rotatable housing, a ratchet wheel rotatable in said housl ing, a pawl pivoted to said housing, spring means urging said pawl into engaged relation with said ratchet wheel whereby to connect said parts for joint rotation, said pawl having an actuating finger thereon, a pawl trip movably mounted apart from said housing and normally disposed in the path of movement of said pawl finger, means for moving said pawl trip out of the path of said pawl finger, and a spring-biased detent movably mounted on said housing and operable, when'said pawl trip is moved out of the path of said pawl finger, to prevent the immediate return of said pawl trip to its said normal position.

2, In a clutch assembly including a rotatable member, a ratchet wheel, a pawl pivoted to said member for movement into and out of engaged relation with said ratchet wheel, spring means urging said pawl into engaged relation with said ratchet wheel whereby to connect said member and wheel for joint rotation, said pawl having an actuating finger thereon, a pawl trip movably mounted apart from said member and wheel, said pawl trip being normally disposed in the path of rotation of said pawl finger for engagement thereby to effect the release of said pawl from the ratchet wheel, means for moving said pawl trip to free said pawl for reengagement with the ratchet wheel, and a spring-biased detent mounted on said member for engagement with said pawl trip, said detent coacting with said pawl trip and being operable, when the latter is moved free of said pawl to delay the return of said pawl trip to its said normal position.

3. In a clutch of the character described including a rotatable housing, a ratchet wheel rotatable in said housing, a pawl pivoted to the housing, spring means for uring said pawl into engaged relation with said ratchet wheel whereby to connect the housing and wheel for joint rotation, one by the other, said pawl having an Also switch 43 is in open condition,

actuating finger projecting radially through an opening in the rim of the housing, a pawl trip movably mounted apart from said housing, said pawl trip normally seating on the rim of said housing in the path of rotation of said pawl actuating finger, whereby said trip is adapted to engage and effect the release of said pawl from the ratchet wheel, manual means for moving said pawl trip to release said pawl actuating finger, and means for temporarily restraining said pawl trip from reengaging said pawl actuating finger, said means comprising a spring-biased detent mounted for limited pivotal movement on the housing, said pawl trip being adapted to engage and efiect movement of said detent to a cooked position, said detent being adapted to spring back, when released by movement of the pawl trip from its normal position, to a position such as to block the return of said pawl trip to its normal position.

4. In combination, an electric motor, clutch means for operatively connecting. said motor to a shaft to 'be driven thereby, said means including a circular clutch housing having an opening in the rim thereof, a ratchet wheel in said housing, connected for rotation by said motor, a pawl pivoted between its ends to the housing, said pawl terminating at one end in a tooth for engagement with the ratchet wheel and at its opposite end in an actuating finger that projects through said housing opening, spring means urging said pawl into engaged relation with said ratchet wheel, control means for said clutch and motor comprising a control lever fulcrumed between its ends to a stationary support, said lever having a laterally projecting nose at one end arranged normally to bear on the rim of said housing, said lever nose being adapted to enter said housing opening and thereafter engage and effect displacement of said pawl to ratchet-free position, a motor control switch, and means connecting said switch for operation by said control lever, said lever being rockable about its fulcrum from a switch-closed position when its nose portion bears upon the rim of the clutch housing to a switch-open position when its nose portion enters said housing opening.

HAROLD P. HOLT. 

